The present invention relates to an electronic module having a flexible printed circuit board, with two-sided component population, bonded to an internally ribbed, integral heat sink.
Electronic packages containing externally-finned heat sinks are well known, with recent examples being described and illustrated in U.S. Pat. Nos. 5,003,429 (Baker et al.) and 4,177,499 (Volkmann). Also well known are modules having a ribbed heat sink and a printed circuit board populated on both sides with electrical components, as described and illustrated in U.S. Pat. No. 4,837,664 (Rodriguez et al.). These patents do not disclose the advantages of a design comprising an internal rib structure, combined with external fins, which allows for improved heat dissipation over devices available previously.
Many devices on the market currently, however, lack the durability necessary to perform well in an underhood automotive environment. In addition, many modules contain surface-mounted power drivers in combination with externally-connected power drivers. Such an arrangement may require numerous types of assembly equipment and, as a result, may be difficult to manufacture. Further, externally-connected power drivers do not dissipate heat as well as surface-mounted power drivers--those mounted directly on a printed circuit board which, in turn, contacts a heat sink.
The aforementioned patent issued to Rodriguez et al. discloses dual grid partitions which may be constructed of thermally conductive material. These grid partitions are not in contact with a heat sink and require that a cover be mounted over each in order to protect the electrical components contained on a thermal plane sandwiched between the partitions. Additionally, the device is unable to accommodate thermally conductive material within the grid partition without leakage due to the open-ended cavities within the grid. The presence of thermally conductive material in proximity to electrical components aids in the dissipation of heat away from the components.
It is seen, therefore, that there is a need for design improvements, including greater resistance to stress and vibration, increased heat transferability, and improved ease of assembly and manufacture.